The present invention relates generally to a method of decreasing gaseous pollutants released into the atmosphere, and, more particularly, to a method of desulfurizing combustion gases produced by the burning of a sulfur-containing fuel.
The ever-increasing awareness that sulfurous gaseous pollutants may pose a significant environmental risk has led to governmental regulation of acceptable levels of sulfur which can be released into the atmosphere. As a result, various schemes for desulfurizing gaseous products of combustion of sulfur-containing fuels, hereinafter referred to as combustion gases, have been developed to reduce the levels of sulfur in combustion gases released into the atmosphere.
Most methods for desulfurizing combusition gases have focused on the addition of sulfur-capturing oxide compounds such as calcium oxide (lime) and magnesium oxide into the combustion chamber. These compounds react with sulfurous gases produced during combustion to form solid sulfur-containing products which can be filtered out from the gases released into the atmosphere. Enhancement of desulfurization by these additives has also been achieved by slaking the oxide compounds to form their hydroxides which more effectively capture sulfur from the combustion gases.
Although additives such as calcium oxide and magnesium oxide are quite effective in removing sulfur from combustion gases, these compounds are relatively expensive and their use on a large commercial scale is cost-prohibitive. Thus, less expensive additives such as calcium carbonate or magnesium carbonate, or these compounds in the raw state, i.e. limestone and dolomite, are more feasible for large-scale use from a cost standpoint. Although less expensive, however, these additives suffer from a low efficacy rate of sulfur removal and thus require use of inordinately large stoichiometric amounts of additive. The use of such large amounts drives up the cost and creates additional problems such as disposal of spent additives.
It would thus be advantageous to provide a relatively inexpensive and simple process which optimizes the conversion of carbonate compounds to their more reactive oxides and results in substantial desulfurization of combustion gases by these compounds.